Abstract: In an injection process, molten resin is successively injected from a first flow channel and a second flow channel connected with each other in order into a cavity of a metal mold. High-temperature resin existing in the first flow channel is injected in advance into the cavity as a part of a single shot of molten resin to later form a skin layer of a molded article. Other low temperature resin near a flowable limit existing in the second flow channel is subsequently injected into the cavity as another part of the single shot of molten resin to later form a core layer of the molded article. A low temperature resin remaining in the first flow channel when injection is completed is warmed to be a high-temperature resin before the next cycle, thereby allowing successive molding of molded articles.

Abstract: In a vent-free single-duct drainage piping system for vertical installation in multi-storied buildings with horizontally extending branches to receive drain from sources of different floors of the building installed, a joint for connecting vertical pipe sections of the drainage piping system is disclosed, which comprises an upper pipe portion having a spiral axis between opposite end portions thereof and adapted for connection to the upstream side of the vertical drainage system to receive drain therfrom. A lower pipe portion is comprised of a first vertical passage connected in direct fluid flow relationship with the upper pipe portion and a second vertical passage having at a side thereof side ports adapted for connection to horizontal drainage pipes laid at a particular floor of the building. The first vertical passage receives drain from the upper pipe portion and the second vertical passage receives drain from the horizontal pipes.